S. Yoon

Publications (2)3.84 Total impact

• Article: Heteroepitaxial growth of Ba1-xSrxTiO3/YBa2Cu3O7-x by plasma‐enhanced metalorganic chemical vapor deposition

  C. S. Chern, S. Liang, Z. Q. Shi, S. Yoon, A. Safari, P. Lu, B. H. Kear, B. H. Goodreau, T. J. Marks, S. Y. Hou
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  ABSTRACT: Epitaxial Ba 1-x Sr x TiO 3 (BST)/YBa 2 Cu 3 O 7-x heterostructures with superior electrical and dielectric properties have been fabricated by plasma‐enhanced metalorganic chemical vapor deposition (PE‐MOCVD). Data of x‐ray diffraction and high resolution transmission electron microscopy showed that 〈100〉 oriented Ba 1-x Sr x TiO 3 layers were epitaxially deposited on epitaxial (001) YBa 2 Cu 3 O 7-x layers. The leakage current density through the Ba 1-x Sr x TiO 3 films was about 10^-7 A/cm² at 2 V (about 2×10⁵ V/cm) operation. Moreover, the results of capacitance‐temperature measurements showed that the PE‐MOCVD Ba 1-x Sr x TiO 3 films had Curie temperatures of about 30 °C and a peak dielectric constant of 600 at zero bias voltage. The Rutherford backscattering spectrometry and x‐ray diffraction results showed that the BST film composition was controlled between Ba 0.75 Sr 0.25 TiO 3 and Ba 0.8 Sr 0.2 TiO 3 . The structural and electrical properties of the Ba 1-x Sr x TiO 3 /YBa 2 Cu 3 O 7-x heterostructure indicated that conductive oxide materials with close lattice to Ba 1-x Sr x TiO 3 can be good candidates for the bottom electrode.
  Applied Physics Letters 07/1994; · 3.84 Impact Factor
• Article: Epitaxial Growth of Ba1−xSrxTiO3 Thin Films on YBa2Cu3O7−x Electrode by PE-MOCVD

  C.S. Chern, S. Liang, Z.Q. Shi, S. Yoon, A. Safari, P. Lu, B.H. Kear
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  ABSTRACT: Plasma-enhanced metalorganic chemical vapor deposition (PE-MOCVD) has been successfully employed for the deposition of (100) oriented barium strontium titanate (BST) thin films on a variety of substrate and electrode materials. The incorporation of O2 plasma, which was used as oxidation reactant, has helped to reduce the required temperature for deposition of high-quality STO and BST thin films. This low temperature processing may make it possible to integrate BST on Si and GaAs. BST films with low leakage current densities of about 10−7 A/cm2 at 2-volt (about 105 V/cm) operation were obtained from PE-MOCVD processing. Moreover, the BST results of capacitance-temperature (C-T) measurements show that most of the PE-MOCVD BST films have Curie temperatures of about 30–35°C and a peak dielectric constant of 600–800 at zero bias voltage, The sharp transition in the C-T data indicates that the BST films may have a high induced pyroelectric coefficient at room temperature, which is highly desirable for uncooled IR imaging arrays. The x-ray diffraction and Rutherford backscattering spectrometry results show that the BST film composition reproducibility was well controlled at around Ba0.75Sr0.25TiO3 with a 4% variation. Device quality BST thin films with the thickness of 1000–2000 Å were produced. These results indicate that PE-MOCVD has high potential to be further developed and promoted as a production deposition technique providing high permittivity dielectric thin films for microelectronics and IR sensor industries.
  MRS Proceedings. 12/1992; 335.